{"id":"CVE-2026-97926","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nufs: validate cylinder group metadata before caching it\n\nufs_read_cylinder() copies the cylinder group index and the rotor\npositions straight from the on-disk group and…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nufs: validate cylinder group metadata before caching it\n\nufs_read_cylinder() copies the cylinder group index and the rotor\npositions straight from the on-disk group and…","severity":"high","cvss":7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H","cwe":["CWE-787"],"vendor":"Linux","product":"Linux","affected":["Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 88cccb6beba136b73f0caf80e59457e1b3c0ca1e","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f560a9e33365c460827c735fd86435f9213f1aed","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < e4c5cc9688c3e69d07d888853388549ae26c0521","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 58c0c414b2b8d099d33da494a354fa836ca6c10b","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5902a95066883cf96fa15b2680694fc5dd0c7d11","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 87b12dc360a002eb2d498aa4f01e84347019612d","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < abde9eb33106850dfa367ad3965d3588bb8558d5","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c9d263be26806d388129fab8c6904bed197fc6af","Linux 2.6.12"],"published":"2026-09-25","updated":"2026-10-03","sourceUpdated":"2026-10-03T11:18:10.417","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-97926","references":[{"url":"https://git.kernel.org/stable/c/58c0c414b2b8d099d33da494a354fa836ca6c10b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5902a95066883cf96fa15b2680694fc5dd0c7d11","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/87b12dc360a002eb2d498aa4f01e84347019612d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/88cccb6beba136b73f0caf80e59457e1b3c0ca1e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/abde9eb33106850dfa367ad3965d3588bb8558d5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c9d263be26806d388129fab8c6904bed197fc6af","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e4c5cc9688c3e69d07d888853388549ae26c0521","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f560a9e33365c460827c735fd86435f9213f1aed","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97926.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-97926"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2541308"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-97926"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97926"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-97926.mbox"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00154,"epssPercentile":0.04444,"ingestedAt":"2026-09-25T11:06:38.887Z","slug":"CVE-2026-97926","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nufs: validate cylinder group metadata before caching it\n\nufs_read_cylinder() copies the cylinder group index and the rotor\npositions straight from the on-disk group and caches them without any\ncheck:\n\n\tucpi->c_cgx    = fs32_to_cpu(sb, ucg->cg_cgx);\n\tucpi->c_rotor  = fs32_to_cpu(sb, ucg->cg_rotor);\n\tucpi->c_frotor = fs32_to_cpu(sb, ucg->cg_frotor);\n\tucpi->c_irotor = fs32_to_cpu(sb, ucg->cg_irotor);\n\nThey are then used as indices during allocation and free:\n\n  - c_cgx indexes the cylinder summary array as\n    UFS_SB(sb)->fs_cs(ucpi->c_cgx), so a value past s_ncg writes a 32\n    bit count outside the s_csp allocation.\n\n  - c_frotor becomes a bitmap scan start, start = c_frotor >> 3, and\n    then length = ((s_fpg + 7) >> 3) - start. A start beyond the block\n    bitmap wraps the unsigned length to a huge value, so ubh_scanc()\n    walks far past the cylinder group buffers. c_irotor drives the\n    inode bitmap the same way.\n\nA crafted image can set any of these freely, turning an ordinary\nallocation into an out of bounds access.\n\nReject a cylinder group whose recorded index does not match the group\nbeing read, or whose rotors fall outside the group, before the metadata\nis cached. Valid filesystems keep cg_cgx equal to the group number and\nthe rotors within the group, so only malformed images are rejected.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 6 · no fix planned: Red Hat Enterprise Linux 6 · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97926.json)","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":38.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":210954,"id":"CVE-2026-97926","ts":1790349118633,"field":"cvss","old":null,"new":"7"},{"seq":210953,"id":"CVE-2026-97926","ts":1790349118633,"field":"severity","old":"none","new":"high"}]}